Paper
16 July 2010 Quantum efficiency measurements of eROSITA pnCCDs
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Abstract
For the eROSITA X-ray telescope, which is planned to be launched in 2012, detectors were developed and fabricated at the MPI Semiconductor Laboratory. The fully depleted, back-illuminated pnCCDs have an ultrathin pn-junction to improve the low-energy X-ray response function and quantum efficiency. The device thickness of 450 μm is fully sensitive to X-ray photons yielding high quantum efficiency of more than 90% at photon energies of 10 keV. An on-chip filter is deposited on top of the entrance window to suppress visible and UV light which would interfere with the X-ray observations. The pnCCD type developed for the eROSITA telescope was characterized in terms of quantum efficiency and spectral response function. The described measurements were performed in 2009 at the synchrotron radiation sources BESSY II and MLS as cooperation between the MPI Semiconductor Laboratory and the Physikalisch-Technische Bundesanstalt (PTB). Quantum efficiency measurements over a wide range of photon energies from 3 eV to 11 keV as well as spectral response measurements are presented. For X-ray energies from 3 keV to 10 keV the quantum efficiency of the CCD including on-chip filter is shown to be above 90% with an attenuation of visible light of more than five orders of magnitude. A detector response model is described and compared to the measurements.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stefanie Ebermayer, Robert Andritschke, Johannes Elbs, Norbert Meidinger, Lothar Strüder, Robert Hartmann, Alexander Gottwald, Michael Krumrey, and Frank Scholze "Quantum efficiency measurements of eROSITA pnCCDs", Proc. SPIE 7742, High Energy, Optical, and Infrared Detectors for Astronomy IV, 77420U (16 July 2010); https://doi.org/10.1117/12.856939
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Cited by 5 scholarly publications.
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KEYWORDS
Quantum efficiency

Photons

Absorption

Sensors

X-rays

Aluminum

Signal attenuation

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